This invention generally relates to pumps with impellers and in particular to an elastomeric water pump impeller used in appliances.
Dishwashers and washing machines use water pumps with impellers to move liquid through and out of the appliance in a series of wash, rinse, and drain cycles. Such pumps include a housing, a rigid cover, an elastomeric impeller molded around a rigid impeller insert for slip fitting onto a rotatable drive shaft or motor shaft, a mechanical face seal consisting of a seal head assembly and a seal seat for preventing liquid leakage between the fixed housing and the rotating impeller, and a two-piece thrust bearing, one half mounted in the impeller for running against the other half mounted in the rigid cover. This thrust bearing resists the axial force of the mechanical face seal and also establishes the axial running clearances of the impeller with both the housing and the rigid cover as well as determining the axial operating height of the mechanical face seal assembly.
Conventional water pumps rely on a controlled cross-sectional squeeze of a fixed integral elastomeric radial rind molded into the inner diameter of the rigid impeller insert to provide retaining, static sealing, and positive rotational drive functions between the inner diameter of the impeller insert and the seal seat outer diameter. Additionally, this cross-sectional squeeze requirement is very precise which often necessitates centerless grinding of the seal seat's outer diameter. However, this system is complex and costly. Thus, there is a need for a simpler, more cost effective and reliable water pump for appliances that is easier to fabricate and faster to assemble.